Lesson 11: Harvesting Timber Products

Transcription

1 Lesson 11: Harvesting Timber Products TEACHER: SCHOOL: GRADE LEVEL: 9-12 TASKS/COMPETENCIES ANR Demonstrate ability to fell trees according to cutting patterns, using chain saw. ANR Demonstrate ability to limb and top felled trees. ANR Make bucking cuts. ANR Plan logging activities. ANR Describe disadvantages and advantages of forest harvesting methods. ANR Manage a forest-harvesting plot. ANR Outline procedures for supervising the loading and unloading of logs. OBJECTIVES AND GOALS The student will define terms associated with harvesting timber. The student will identify how to make a tree fall in a predetermined direction. The student will demonstrate how to make a tree fall in a predetermined direction. SOL CORRELATIONS Earth Science ES.7 (renewable and nonrenewable resources) English 9.2 (oral presentations) 10.7 (variety of writings) (collect, evaluate, and organize information) 11.8 (personal and business correspondence) 12.1 (oral presentations) 12.7 (expository and technical writings) Civics and Economics CE.9 (economic decisions in the marketplace) Mathematics A.4 (use of matrices) EQUIPMENT, SUPPLIES, AND MATERIALS NEEDED Chain saw Hammer Wedges Instructor-prepared vocabulary list Instructor-provided checklist for evaluating harvesting plans The student will state reasons for harvesting trees from noncommercial forestlands. The student will describe the shortwood and longwood systems used in logging. The student will identify factors that affect the cost of hauling logs. The student will describe and identify advantages of total tree chipping. The student will explain how to determine bucking cuts for crooked logs. 93

2 ACTIVITIES Preparation Lesson approach A commercial forest is managed to produce a timber crop. When the crop is mature, it should be harvested and a new crop allowed to grow. ging the timber crop is as much a part of good forest management as planting, fire protection, or timber stand improvement. ging is as important to the commercial forest as harvesting is to the farm. Even in forests managed primarily for recreation, harvesting is needed. Intermediate cuttings keep the stand in top shape, open the stand to light, and establish undergrowth needed for wildlife production. Harvesting removes the trees at maturity, before they start the decline, which makes them more susceptible to disease and insects. ging in a commercial forest, to be economical, must obtain the greatest return at the least cost. Many times this means the stand, or some portion of it, must be clear-cut. The scar left by a clear-cut operation is a temporary situation and, in a commercial operation, will soon be covered by a new forest. Improper harvesting methods can turn a well-managed, high-quality stand into low-grade timber. Through proper harvesting and regeneration, the forest resource is perpetuated. General situation The planning of a logging operation should be done by a professional forester. The plans for the harvest should be a part of the total management plan for the timber stand. Harvesting is probably the most hazardous job in the total forest production cycle. Local situation Determine what harvesting operations are being conducted or planned in the local area. Identify these by the type of cutting practice, and determine the silvicultural benefits if it is an intermediate cutting. Identify the end-use markets of the timber being cut, its approximate value per MBF delivered to the processing plant, and the component costs of the harvesting operation. Determine who the local logging contractors are and the size and types of equipment and crews that they use in their operation. Application Arrange field trips to forest areas to observe various stages of harvesting and the use of the equipment. Arrange opportunities for students to use both portable and large mechanized equipment for harvesting operations. Visit several stands of timber of various ages and types and have students recommend method of harvesting and give reasons. List procedures or steps necessary to develop a harvesting plan; explain requirements for this section of long-term projects. 94

3 Presentation: Harvesting Plans Selecting trees to be cut Review the material presented in Lesson 6, paying special attention to the sections on intermediate cuttings and harvest cutting. It is important to note closely the selection of the trees to be cut or left in each cutting class. Identify and suggest examples of each cutting type being done in the local area. Planning the operation Planning a logging operation can be the most important part of the total harvesting procedure. Initial planning can reduce the total logging cost and increase the efficiency of the operation. A balance between the various operations in harvesting must be maintained and accurate information on production must be available in order to achieve this. The table below depicts a typical operation and shows how the various components have been balanced. Operation control It is important that a balance be maintained in all areas of operation. For example, adding more workers in the felling and bucking operation will not increase production unless similar increases are made in other operations, such as bunching or skidding. ging system design table Operation Equipment * per unit Production (MBF/day) Number of units for a balanced system Total production (MBF/day) Felling & bucking Power saw, 6-hp class Bunching & decking 58 DB, rubber-tired skidder Skidding Same equipment used for B&D above (capacity approximately 0.60 MBF) Loading Hydraulic, tractor mounted (approximately 0.20 MBF capacity) Hauling (50 mi.) 41,000 No. GVW, 190-hp truck with trailer (approximately 4.0 MBF capacity) * Abbreviations used are hp, horsepower; DB, drawbar; B&D, bunching and decking: MBF, thousand board feet; GVW, gross vehicle weight; No., pounds. ging systems Harvesting is composed of several integrated operations, each one having numerous possible approaches that can be used. The proper organization of the individual operations into the total harvesting operation represents the logging system. Basically, two logging operations can be considered: pulpwood harvesting and sawlog harvesting. The two operations might be conducted independently or simultaneously; additionally, both types of operations can be subdivided into two types of operations. Shortwood system The log is bucked into pulpwood or sawlog length at the stump and is moved from stump to mill in short lengths. Longwood system The log is hauled from the woods in tree length and is either bucked at the landing and hauled to the mill in short lengths, or it is loaded and hauled in long lengths and bucked at the mill. 95

4 Felling trees Felling is the initial operation in the manufacturing of wood products. Today, felling is usually performed by one- or twoworker teams, using chain saws. Under normal conditions, a single worker is more efficient than a two-person team. With the development of hydraulic shear cutters and machinery designed for tree felling, the operation is becoming increasingly mechanized. Hydraulic Tree Shear Mechanized felling Tractor-mounted tree shear A tree shear is a hydraulically operated blade that cuts against a fixed anvil. Shears can be mounted on skidding or bunching tractors or on a tractor used only for felling. Some shears will cut timber up to 24 inches in diameter. Harvesting machine Several manufacturers are currently marketing tree-harvesting machines. Two general concepts of harvesting machines are being utilized. Feller-buncher The feller-buncher has a felling head which clamps the tree at the base and at several points up the stem. A shear is incorporated on the felling head, and the tree can be lifted and placed in an overhead rack after the cut is made. The machine moves from tree to tree, adding each to its load until a full load is gathered. The load can then be moved to a landing or may be dropped for pickup by a skidder. Tree harvesters The tree harvester incorporates additional equipment to limb, fell, buck, and stack the cut-to-length wood. The machine will normally cut and stack a load or pallet of wood and drop it for movement to the landing by other machinery. Limitations Normally the more complex the harvesting machine, the more dependent it is on terrain and conditions. A skidder-mounted shear can log most stands on which skidders can normally operate. On the other hand, a tree harvester is generally limited to flat or slightly sloped terrain, attaining its most efficient production in a plantation type of stand. Hand felling Felling crew A feller equipped with a chain saw is responsible for felling and limbing the tree. In a shortwood system, the feller may also be responsible for bucking the tree to log or pulpwood length. Felling operation layout The general layout of the felling operation is very important and is the responsibility of the logging supervisor. Proper layout can save both time and work and is vitally important for the safety of the crew. Layout should be such that each crew member of the felling team works at a safe distance from all others. Trees should be felled in a manner that permits them to be easily reached by the skidders and still allow the fellers to progress through the stand. Direction of fall Before starting to saw, the feller should examine the tree to determine direction and location of the drop. A tree with well balanced limbs around the bole that leans no more than 5 degrees can usually be dropped in any direction. This is done by properly locating the undercut, wedging, and controlling the back cut. Normally, trees that lean more than 5 degrees 96

5 or have unbalanced branching can be directed only 45 degrees to either side of the direction of the lean or center of weight. Back cut Undercut 45 angle Back cut Undercut Normally a tree should not be felled straight up or straight down a steep slope. Under normal conditions, a tree felled straight up a slope may kick back over the stump and hit the feller, and trees felled straight down are subject to shattering in the fall. Trees should not be dropped across a rock, stump, or another log because the trunk may break. Work space clearance Brush and low-hanging branches should be cleared from the area around the base of the tree and a safe line of retreat should be made available. Tree cutting Undercut The undercut is made on the side of the tree, in the same direction that the tree is to fall. The undercut should provide a 45-degree notch with the bottom cut flat and the top cut angled, and it should extend to a depth of about one-quarter the diameter of the tree. Backcut The backcut should be made two to four inches above the base of the undercut. The cut should continue into the tree until two or three inches of holding wood is left. If the tree has not begun to fall, it should then be wedged by driving one or two wedges behind the saw. Leaning trees can be directed by wedging on the leaning side of the backcut or by leaving a holding corner. The holding corner is made in the backcut by leaving more wood on the side that is opposite the lean of the tree. Rotten trees Special care should be taken in felling trees with butt-rot. If possible, the cut should be made high enough to avoid the rot. If this is not possible, the backcut should be made by carefully sawing several cuts around the trunk. Lodged trees A felled tree that lodges in a standing tree is potentially hazardous, and care should be taken to prevent this from occurring. The safest and most practical method of dislodging a tree is by pulling it out with a skidder or wench. Never climb the trunk and try to shake it loose or attempt to cut the tree in which the first one is lodged. Limbing and bucking The felling crew usually does limbing at the felling site. The felling crew may do bucking, or the logs may be moved full length to be bucked at the landing or the mill. Bucking at the mill With the development of forest product complexes, the trend is toward tree-length logging with the bucking being done at the plant site. Bucking can then be done by large power-driven crosscut saws, and a trained worker can make the bucking decision. The cuts can be made to allow for maximum utilization of the log in one of several plants. Peeler logs can be cut and sent to the plywood mill, sawlogs to the lumber mill, and tops and cull sections can be chipped for pulp. 97

6 Bucking at the landing In many instances it is more economical to move tree-length logs to the landing. The bucking can then be done by special machines or trained bucking crews. In tree-length logging, tops can be brought in with the sawlog, then segregated for pulp at the landing. Bucking at the stump Bucking of pulpwood in the field is a matter of cutting the bole to the desired pulpwood length; cutting out undesirable defects, such as charred areas; and continuing up the bole to the minimum allowable top diameter. Bucking of sawlogs or veneer logs is a more critical task. Proper bucking can maximize the value of a tree and improper bucking can severely decrease the value. Bucking alternatives crooked logs A B 15" 13" 16" 16" Grade Dia. (in.) Length (ft.) Gross Scale (O.L.R.) Not Recommended Net Scale (O.L.R.) Value Lbr.Value (per log) Lbr. Value (per MBF net scale) Lbr. Value per Gross Cu. Ft. of Volume A F B F Total (and average) for tree (128.56) (0.54) (a) C D (b) E 16" 13" 14" 10" 12" 10" Grade Dia. (in.) Length (ft.) Gross Scale (O.L.R.) Recommended Net Scale (O.L.R.) Value Lbr.Value (per log) Lbr. Value (per MBF net scale) Lbr. Value per Gross Cu. Ft. of Volume C F D F E F Total (and average) for tree (145.86) (0.92) 98

7 Handling and skidding logs and bolts Pulpwood-shortwood system Truck loading at the stump This is the simplest method of handling pulpwood, and for a one- or two-person pulpwood harvesting crew, it may well be the cheapest way of producing pulpwood. Prehauling In a shortwood system using a larger crew, the pulpwood can be stacked on pallets by the felling-bucking crew and then picked up by a prehauler and moved to the landing. The prehauler may be a specially designed tractor built to carry one or more pallets, or it may be a tractor pulling the pallets on skids. Tree-length skidding The logs are skidded to the landing by crawler tractors or rubber-tired skidders. If the logs are widely scattered, a bunching tractor may be used to move the logs together to allow the skidder to pick up a full load. If the logs are close together at the logging site, the bunching can be done with a power winch on the skidder. Bunching and short skids can be made by dragging the logs behind a tractor. On long skids, the leading end of the logs should be raised off the ground. This is usually done with a logging arch which is high enough to lift the front end of the load from the ground. On most machines designed for skidding, the arch is an integral part of the machinery. Securing the log is done by either using a wire rope looped over the log end, called a choker, or by a hydraulic grapple mounted on the skidder, called chokerless skidding. Sawlogs Sawlogs are usually skidded to a landing either in log lengths or tree lengths. The skidding practice is similar to that used in tree-length pulpwood skidding. Loading the timber The loading operation in most logging operations is mechanized. Occasionally on small pulpwood operations, loading may still be done by hand. Truck-mounted loaders In a one- or two-truck operation from a landing and in most pulpwood operations loading at the stump, truck-mounted loaders are used. Since the truck driver serves as the loader operator, a worker and separate machine do not sit idle at the landing waiting for the truck to make a round trip to the mill. Loaders Operations involving several trucks are better suited to the use of one of the many available types of loaders. These fall into two general groups front-end loaders mounted on tractors, and boom or crane loaders, either on truck bodies or as selfpropelled units. Hauling the timber Several variables affect the cost of log hauling. To determine the proper size and number of trucks, the following should be considered. Material The truck should be designed to carry the material being hauled. Pulpwood bolts, logs, tree-length pulpwood, and tree-length sawtimber all may require different types of truck. Delay and standby Some delay and standby time while waiting for loading and unloading is unavoidable. Care in planning and scheduling of trucks to the landing and delivery point can minimize these delays. Hot loading (loading directly from the skidder to the truck) can cause delays. This can be avoided by maintaining enough logs at the landing to load all trucks as they arrive. Length of haul On short hauls, smaller trucks are more economical; on long hauls, larger trucks are better. This is because the loading and unloading time on short hauls represents a higher percentage of the total hauling time. Road standards A haul involving high mileage in woods and on secondary roads will be more expensive and require more trucks than a haul made essentially on paved roads. 99

8 Chipping the total tree Total tree chipping requires a special piece of equipment designed to chip trees up to 22 inches in diameter. The trees are severed at the stump and then skidded to the chipper. The chipper has grapples that pull the butt end of the tree into the mouth of the chipper. Rollers then feed the total tree into the body of the machine, where it is converted to chips. The chips are blown from the machine into a tractor-trailer van and transported directly to the pulp mill. A total tree harvesting and chipping operation uses practically all the wood fiber on the site, thus making it more convenient and less costly to prepare the area for tree planting. ADDITIONAL ACTIVITIES Have students define terms related to logging and hauling timber. Arrange a field trip to a logging site so students can observe the equipment used in felling, limbing, and bucking operations. Discuss and demonstrate how to determine the direction of fall for a felled tree. Have students outline felling procedure to make trees fall in various directions. Discuss safety hazards connected with the felling of trees and how to avoid kickback and lodging; emphasize procedures for dealing with leaning, rotten, and lodged trees. Discuss and compare the shortwood and longwood systems of harvesting. Review information on intermediate cutting in Lesson 6, and discuss both tree selection and reasons for harvesting trees in noncommercial forests. Discuss the cost factors associated with hauling logs. Arrange for students to observe chipping operation, and discuss the advantages of total tree chipping. Demonstrate and have students practice felling, limbing, and bucking operations; demonstrate or discuss how to determine bucking cuts in crooked logs. SUGGESTIONS FOR STUDENT EVALUATION Student should fell one or more trees. Student should limb and top one or more felled trees. Plan of logging activities should include the following and be rated acceptable according to instructor-prepared checklist: rough sketch of tract with roads and clearings marked procedure for tree selection and product(s) to be sold market location types and numbers of workers and equipment needed plans for felling, limbing, and bucking schedule and plans for loading, hauling, and unloading estimated time schedule for logging activities and clean-up safety regulations and precautions to be observed. SUGGESTED RESOURCES Determining Fixed and Operating Costs of ging Equipment. USDA, Forest Service Felling and Bucking Hardwoods How to Improve Your Profit. Department of the Environment Canadian Forestry Service Fundamentals of ging. Allis-Chalmers Handbook of Eastern Timber Harvesting (pp ). USDA, Forest Service Health and Safety Code Handbook. USDA, Forest Service Pulpwood Production. W. S. Bromley

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